In data transmission networks, supervision functions are provided to ensure integrity of data transfers. For instance, in a network including a Control Station to which a number of data terminals are attached, the transmission from any terminal to the Control station may be organized using a polling technique. This technique may be implemented through the cyclic scanning of a list of terminal addresses.
At each polling cycle data are effectively transferred only when the terminal involved is polled and the polled terminal wishes to transmit at that very instant.
This, obviously is time consuming since at each polling cycle, time is devoted to polling terminals which do not wish to transmit. The greater the number of terminals attached to the network, the higher the time consumed... This process is more particularly inefficient when the attached terminals are low traffic rate terminals attached to the network through a high speed (HS) channel.